CN112442000A

CN112442000A - Integrated reactor and method for preparing furfural and levulinic acid by using agricultural and forestry waste biomass in grading manner

Info

Publication number: CN112442000A
Application number: CN202011405056.7A
Authority: CN
Inventors: 马隆龙; 张兴华; 王晨光; 张琦; 陈伦刚; 刘琪英; 杨彬
Original assignee: Guangzhou Institute of Energy Conversion of CAS
Current assignee: Guangzhou Institute of Energy Conversion of CAS
Priority date: 2020-12-02
Filing date: 2020-12-02
Publication date: 2021-03-05
Anticipated expiration: 2040-12-02
Also published as: CN112442000B

Abstract

The invention discloses an integrated reactor and a method for preparing furfural and levulinic acid by using agricultural and forestry waste biomass in a grading manner. The integrated reactor comprises a reactor barrel, wherein a steam inlet spray pipe is arranged on the lower portion of the reactor barrel, a steam outlet regulating valve is arranged at the top of the reactor barrel, a mechanical stirring system is arranged on the reactor barrel and comprises a stirrer and a motor, the stirrer is arranged inside the reactor barrel, the motor drives the stirrer to rotate, and a biomass raw material inlet and an acid liquor replenishing inlet are formed in the top of the reactor barrel. The invention designs and develops a novel stripping-hydrolysis integrated depolymerization reactor based on the difference of depolymerization activation energy of cellulose and hemicellulose in biomass, provides a new thought of stepwise depolymerization and conversion of agriculture and forestry waste biomass, realizes the optimized matching of energy supply and substance conversion in the stepwise conversion process, and solves the problem of inconsistent requirements of hemicellulose stripping and cellulose hydrolysis conversion on process operation parameters.

Description

Integrated reactor and method for preparing furfural and levulinic acid by using agricultural and forestry waste biomass in grading manner

Technical Field

The invention relates to the technical field of biomass energy, in particular to an integrated reactor and a method for preparing furfural and levulinic acid by using agricultural and forestry waste biomass in a grading manner.

Background

China is a big country for agriculture and forestry, and the storage of available biomass resources reaches 10 hundred million tons of standard coal per year. The vast amount of agricultural and forestry waste biomass is wasted each year, which brings enormous environmental pressure. For example, the phenomenon of illegal and disordered incineration of a large amount of agricultural and forestry waste is frequently forbidden, and the pollution caused by concentrated incineration of the agricultural and forestry waste under adverse weather conditions is aggravated, so that the haze weather is greatly increased. Therefore, the efficient treatment of the agricultural and forestry waste biomass resources is one of the important contents of environmental governance.

The biomass is the only renewable carbon resource in the nature and has the characteristic of near zero emission. The efficient utilization of biomass is one of the ideal ways to ensure the sustainable supply of clean energy. However, the current biomass raw material conversion process has low efficiency, poor economy and other factors, which limit the scale utilization of the agricultural and forestry waste biomass. The agriculture and forestry waste biomass recycling and high-value utilization technology becomes a key technology in the field of environmental management, and has important significance for improving the environment, meeting the supply of clean energy, reducing the dependence on external crude oil and other national strategic demands.

In the utilization process of biomass, the efficient directional depolymerization and conversion of the biomass into platform compounds and chemicals is an extremely important step. For example, the Chinese patent ZL201610304296.5 provides a new technology for preparing biological aviation oil from lignocellulose biomass through furfural and levulinic acid, and opens up a new way for synthesizing hydrocarbon fuel from lignocellulose raw materials. However, in the process of preparing compounds such as furfural levulinic acid and the like by depolymerizing and converting biomass, the following bottlenecks still exist in the conventional hydrothermal depolymerization technology, and need to be broken through urgently: (1) because the biomass raw material is sensitive to heat, the traditional hydrothermal depolymerization process has more side reactions, the high selectivity of a target product is low, the product is complex, and the separation difficulty is high; (2) the biomass components are complex, under the traditional hydrolysis process of a 'one-pot method', different components are difficult to depolymerize and convert under respective optimal working conditions, the yield of target products is low, and the depolymerization efficiency is low; (3) high energy consumption and large steam consumption, and is not beneficial to industrialized popularization.

Disclosure of Invention

The invention provides an integrated reactor and a method for preparing furfural and levulinic acid by agricultural and forestry waste biomass in a grading manner, and the integrated reactor and the method are based on the depolymerization activation energy difference of cellulose and hemicellulose in biomass, design and develop a novel steam stripping-hydrolysis integrated depolymerization reactor, provide a new idea of gradual depolymerization and conversion of agricultural and forestry waste biomass, realize the optimized matching of energy supply and material conversion in the gradual conversion process, and solve the problem of inconsistent requirements of the steam stripping of the hemicellulose and the hydrolysis conversion of the cellulose on process operation parameters.

The invention aims to provide an integrated reactor for preparing furfural and levulinic acid by using agricultural and forestry waste biomass in a grading manner, which comprises a reactor barrel, wherein a steam inlet spray pipe is arranged at the lower part of the reactor barrel, a steam outlet regulating valve is arranged at the top of the reactor barrel, a mechanical stirring system is arranged on the reactor barrel, the mechanical stirring system comprises a stirrer arranged in the reactor barrel and a motor for driving the stirrer to rotate, a biomass raw material inlet and an acid liquor replenishing inlet are arranged at the top of the reactor barrel, a jacket auxiliary heating system is arranged outside the reactor barrel, the jacket auxiliary heating system comprises a jacket arranged outside the reactor barrel and a jacket steam inlet arranged on the jacket, and a jacket steam outlet is also arranged at the bottom of the jacket. When the stirrer rotates, the biomass raw materials in the reactor can be uniformly stirred in the radial direction and the longitudinal direction.

The reactor provided by the invention is a stripping-hydrolysis integrated reactor, in the traditional furfural preparation technology, in order to ensure the stripping reaction time of raw materials, the height-diameter ratio (the ratio of the height to the diameter) of a stripping tower is generally between 6 and 10, the yield of products is improved by prolonging the stripping time, but the equipment investment and the operation difficulty are increased. The preparation of levulinic acid by biomass hydrolysis is generally carried out in a tank reactor, and as the raw materials are generally not pretreated, the yield of the levulinic acid product is generally improved by means of stirring, increasing the liquid-solid ratio, increasing the temperature and the like in order to increase the conversion efficiency. The invention combines the characteristics of two traditional processes of steam stripping and hydrolysis, determines the optimal range of the height-diameter ratio of the reactor, adopts a novel stirrer and strengthens the heat and mass transfer in the process of biomass raw materials; meanwhile, a new method for preparing furfural and levulinic acid by decomposing, depolymerizing and converting is provided based on the difference of depolymerization temperatures of hemicellulose and cellulose in the biomass raw material. In the new method, the biomass stripping process is equivalent to the pretreatment of the biomass raw material in the hydrolysis process, so that the coupling of biomass stripping and hydrolysis reaction is realized, and the overall efficiency of the whole process technology is improved.

Preferably, the ratio of the height of the reactor cylinder to the diameter of the cylinder is 3-5: 1.

Preferably, the lower part of the reactor cylinder is provided with a plurality of steam inlet spray pipes which are uniformly distributed along the circumference of the cylinder. Further preferably, 4 steam inlet spray pipes are uniformly arranged at the lower part of the reactor cylinder along the periphery of the cylinder. The steam spray pipes are uniformly arranged so as to ensure that steam uniformly enters the reactor and is fully contacted with the biomass raw material.

The bottom of the reactor barrel is provided with a discharge quick-opening valve and a sampling port, and the top of the reactor barrel is provided with a temperature measuring port and a pressure measuring port. The temperature measuring port is connected with a thermocouple extending into the reactor, so that the temperature in the reactor can be measured in real time, the pressure in the reactor can be measured in real time through the pressure measuring port, and smooth reaction is guaranteed.

Preferably, the material of the reactor barrel and the stirrer is acid corrosion resistant material, and the acid corrosion resistant material is hastelloy material, composite plate material lined with hastelloy, steel lined with enamel, pressure-resistant corrosion-resistant material lined with PFA plastic or pressure-resistant corrosion-resistant material lined with polytetrafluoroethylene.

The invention also discloses a method for preparing furfural and levulinic acid by using the agricultural and forestry waste biomass in a grading manner, which is realized by using the integrated reactor for preparing furfural and levulinic acid by using the agricultural and forestry waste biomass in a grading manner, and comprises the following specific steps: uniformly mixing a biomass raw material with a dilute acid solution, feeding the mixture into a barrel through a biomass material raw material inlet, sealing a feed inlet, then opening a motor to drive a stirrer to rotate, introducing saturated water vapor through a vapor inlet spray pipe, and adjusting a vapor outlet adjusting valve to ensure that steam extraction is carried out at the temperature of 140-160 ℃ to prepare furfural; and after furfural stripping is finished, adding acid liquor from an acid liquor replenishing inlet, introducing saturated water vapor through a vapor inlet spray pipe, introducing vapor into a jacket vapor inlet of a jacket auxiliary heating system for auxiliary heating, and regulating the temperature of the reactor to 160-180 ℃ through a vapor outlet regulating valve for hydrolysis to prepare levulinic acid.

The hemicellulose component in the biomass raw material provided by the invention is converted into furfural by stripping depolymerization at a mild condition (140-160 ℃), and the cellulose component is converted into levulinic acid by hydrolysis at a preferred temperature of 160-180 ℃, so that the gradual efficient depolymerization and conversion of different components of the biomass raw material are realized, and the yield of two target products is improved. In addition, because the steam stripping of the hemicellulose and the hydrolysis of the cellulose are carried out in series in the same reactor, the consumption of catalyst sulfuric acid and steam is saved, and the technical economy of biomass hydrothermal depolymerization is greatly improved. The biomass raw materials comprise corn straws, wheat straws, cotton straws, bagasse, wood chips and the like.

Preferably, the dilute acid solution is dilute sulfuric acid solution, the mass fraction of the dilute sulfuric acid solution is 5-15%, and the use amount of sulfuric acid is 0.5-5% of the mass of the biomass raw material; the acid added from the acid liquor replenishing inlet is sulfuric acid, the mass fraction of the sulfuric acid is 5-15%, and the use amount of the sulfuric acid is 0.5-1% of the mass of the biomass raw material.

Preferably, the stirring speed of the stirrer is 5-20 revolutions per minute.

Preferably, the steam extraction time is 30-120 minutes; the hydrolysis time is 30-180 minutes.

Preferably, the pressure of the saturated water vapor is 1.2-1.5 MPa.

Compared with the prior art, the invention has the beneficial effects that: the invention provides a biomass stripping and hydrolysis integrated reactor for preparing furfural and levulinic acid by biomass fractional depolymerization and an application method thereof. The reactor integrates the advantages of a stripping tower and a hydrolysis kettle, the hemicellulose is stripped under a mild working condition to produce the furfural, then the temperature is increased, the cellulose is hydrolyzed to prepare the levulinic acid, the hemicellulose and cellulose components in the biomass raw material are respectively converted into the furfural and the levulinic acid in a high selectivity manner in the same reactor, and the steam consumption is greatly reduced.

Drawings

FIG. 1 is a schematic structural diagram of a stripping-hydrolysis integrated reactor for preparing furfural and levulinic acid by biomass grading;

FIG. 2 is a schematic view of the steam inlet nozzle arrangement of FIG. 1;

description of reference numerals: 1. a reactor barrel; 2. a temperature measuring port; 3. a pressure measurement port; 4. a steam inlet nozzle; 4a, a first steam inlet nozzle; 4b, a second steam inlet nozzle; 4c, a third steam inlet nozzle; 4d, a fourth steam inlet nozzle; 5. a ribbon blender; 6. a discharging quick-opening valve; 7. a sampling port; 8. a jacket steam outlet; 9. a jacket steam inlet; 10. a biomass feedstock inlet; 11. a mechanical agitation system; 12. a steam outlet regulating valve; 13. an acid liquor replenishing inlet; 14. jacket auxiliary heating system.

Detailed Description

The following examples are further illustrative of the present invention and are not intended to be limiting thereof. The equipment and reagents used in the present invention are, unless otherwise specified, conventional commercial products in the art.

As shown in fig. 1 and fig. 2, the stripping-hydrolysis integrated reactor for preparing furfural and levulinic acid by using agricultural and forestry waste biomass in a grading manner is mainly constructed as follows: mainly comprises a reactor barrel 1 and a jacket auxiliary heating system 14, wherein the lower part of the reactor barrel 1 is provided with a discharge quick-opening valve 6 convenient for discharging materials and a sampling port 7 for sampling in the reaction process, the side surface of the bottom of the reactor barrel 1 is provided with 4 steam inlet spray pipes 4, a first steam inlet spray pipe 4a, a second steam inlet spray pipe 4b, a third steam inlet spray pipe 4c and a fourth steam inlet spray pipe 4d are uniformly distributed along the circumference of the reactor barrel 1, the top of the reactor barrel 1 is provided with a steam outlet regulating valve 12, the device comprises a temperature measuring port 2 for measuring the temperature in the reactor in real time, a pressure measuring port 3 for measuring the pressure in the reactor in real time, a biomass raw material inlet 10 and an acid liquor replenishing inlet 13, wherein a mechanical stirring system 11 is further arranged on a reactor cylinder 1, the mechanical stirring system 11 comprises a motor and a stirrer driven by the motor, and the stirrer is preferably a spiral ribbon type stirrer 5 in the invention. The jacket auxiliary heating system 14 comprises a jacket arranged outside the reactor barrel 1 and a jacket steam inlet 9 arranged on the jacket, and a jacket steam outlet 8 is also arranged at the bottom of the jacket.

The height-diameter ratio of the stripping-hydrolysis integrated reactor barrel 1 is 3: 1-5: 1. In the following examples, the reactor barrel preferably has an aspect ratio of 4: 1.

The reactor barrel 1, the ribbon agitator 5 and the pipe fittings contacting with the liquid adopt acid corrosion resistant materials, and the acid corrosion resistant materials include: hastelloy materials, composite board materials lined with hastelloy, steel lined with enamel, pressure-resistant materials lined with PFA plastics and pressure-resistant materials lined with Polytetrafluoroethylene (PEFE). In the following examples, sulfuric acid is a sulfuric acid solution having a mass fraction of 8%.

Example 1

A method for preparing furfural and levulinic acid by using agricultural and forestry waste biomass in a grading manner comprises the following steps: uniformly mixing a corn straw raw material and a dilute sulfuric acid solution, feeding the mixture into a reactor barrel 1 through a biomass raw material inlet 10 (the amount of sulfuric acid is 1% of the mass of the corn straw), sealing a feed inlet, introducing 1.3MPa saturated steam, opening a ribbon stirrer 5, adjusting a steam outlet adjusting valve 12 to the temperature inside the reactor to be 150 ℃, performing steam extraction for 60min under the condition, and collecting steam extract, namely furfural-containing product liquid. After furfural stripping is finished, adding sulfuric acid (the amount of sulfuric acid is 1% of the mass of the corn straws) from an acid liquor supplementing inlet 13, introducing steam for assisting heat at a jacket steam inlet 9 of a jacket assisting heat system 14 at a rotating speed of 10rmp, increasing the temperature and pressure of the reactor through a steam outlet regulating valve 12, and hydrolyzing at 170 ℃ to prepare levulinic acid, wherein the hydrolysis time is 120 min. The furfural yield and levulinic acid yield obtained by the test run are shown in table 1.

Examples 2 to 5

The operation method was the same as in example 1, and the furfural yield and levulinic acid yield obtained by changing the process conditions such as stripping temperature, stripping time, hydrolysis temperature, hydrolysis time and the like were recorded in table 1.

TABLE 1

As shown in Table 1, the yield of furfural and levulinic acid products is high when the stripping temperature is more than or equal to 150 ℃, the hydrolysis temperature is more than or equal to 170 ℃, and the stripping time and the hydrolysis time reach 60 minutes.

Examples 6 to 9

Referring to example 5, the steam stripping temperature is 150 ℃, the steam stripping time is 120min, the hydrolysis temperature is 180 ℃, the hydrolysis time is 120min, the sulfuric acid dosage of the primary acid mixing, the sulfuric acid dosage of the supplementary acid and the stirring rate are changed, and the obtained furfural yield and the levulinic acid yield are recorded in table 2.

TABLE 2

	The amount of the primary acid-mixed sulfuric acid	Yield of Furfural (%)	The dosage of sulphuric acid for acid supplementation	Rate of agitation (rmp)	Levulinic acid yield (%)
						Example 5	1％	11.2	1％	10	15.5
Example 6	1％	11.2	1％	5	14.6
						Example 7	1％	11.2	1％	20	15.5
Example 8	0.5％	4.9	1％	10	13.0
						Example 9	5％	11.9	0.5％	10	15.8

The amount of sulfuric acid in table 2 is expressed as a percentage of straw feedstock.

From table 2, it is found that when the amount of the primary acid-mixing sulfuric acid and the amount of the acid-supplementing sulfuric acid reach 1%, the yield of furfural and levulinic acid is high. When the amount of the sulfuric acid is less, the reaction of the biomass raw material is insufficient, so that the yield of the target products of furfural and levulinic acid is low.

Example 10

Referring to example 5, the amount of sulfuric acid used in primary acid mixing is 2% of the mass of the straw, the stripping temperature is 150 ℃, the stripping time is 120min, and the amount of consumed steam and the yield of furfural are shown in table 3.

Example 11

Currently, furfural in industry adopts a direct stripping process, and a stripping reactor is not provided with a stirring device. For comparison, referring to example 10, the amount of primary acid-mixed sulfuric acid is 2% of the mass of the straw, the stripping temperature is 150 ℃, the stripping time is 120min, the stirrer is not turned on (not stirred), and the yield of furfural when the same amount of steam as that in example 10 is consumed is shown in table 3.

Example 12

Referring to example 5, the amount of sulfuric acid used in primary acid mixing is 2% of the mass of the straw, hydrolysis is directly performed without a steam stripping step, the hydrolysis temperature is 180 ℃, the hydrolysis time is 120min, and the amount of steam consumed, the yield of furfural and the yield of levulinic acid are shown in table 3. For comparison, the total amount of steam consumed, furfural yield, and levulinic acid yield for example 5 are also reported in table 3.

TABLE 3

The sulfuric acid is expressed as percentage of straw material in terms of acid amount, and the total steam consumption is the amount of steam consumed for processing each ton of straw material.

From the data in table 3, 112kg of furfural and 155kg of levulinic acid can be produced by using 1 ton of corn straw raw material by the method, and the steam consumption is only 7 tons; the traditional hydrothermal depolymerization method is used for producing considerable amounts of furfural and levulinic acid by using the reactor disclosed by the invention, 2 tons of corn straw raw materials are needed, and the steam consumption is 11.5 tons. The integrated reactor and the method for preparing furfural and levulinic acid by depolymerizing hemicellulose and cellulose in the biomass raw material step by step save steam by nearly 40 percent.

Example 13

In a steam stripping-hydrolysis integrated reactor with a height-diameter ratio of 8:1, referring to the method of example 5, the amount of sulfuric acid for primary acid mixing is 1% of the mass of the straws, the steam stripping temperature is 150 ℃, the steam stripping time is 120min, the amount of sulfuric acid for acid supplementation is 1% of the mass of the straws, the hydrolysis temperature is 180 ℃, the hydrolysis time is 120min, and the yield of furfural and the yield of levulinic acid are 11.7% and 10.3%, respectively. The reason why the yield of levulinic acid was significantly reduced compared with example 5 was analyzed to be that the aspect ratio was too large, and the raw material at the upper part of the reactor was not sufficiently immersed in high-temperature liquid water, which affected the hydrolysis efficiency.

The above is only a preferred embodiment of the present invention, and it should be noted that the above preferred embodiment should not be considered as limiting the present invention, and the protection scope of the present invention should be subject to the scope defined by the claims. It will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the spirit and scope of the invention, and these modifications and adaptations should be considered within the scope of the invention.

Claims

1. The integrated reactor for preparing furfural and levulinic acid by using agricultural and forestry waste biomass in a grading manner is characterized by comprising a reactor barrel, wherein a steam inlet spray pipe is arranged on the lower portion of the reactor barrel, a steam outlet regulating valve is arranged at the top of the reactor barrel, a mechanical stirring system is arranged on the reactor barrel, the mechanical stirring system comprises a stirrer arranged in the reactor barrel and a motor driving the stirrer to rotate, a biomass raw material inlet and an acid liquor replenishing inlet are formed in the top of the reactor barrel, a jacket auxiliary heating system is arranged outside the reactor barrel, the jacket auxiliary heating system comprises a jacket arranged outside the reactor barrel and a jacket steam inlet arranged on the jacket, and a jacket steam outlet is further arranged at the bottom of the jacket.

2. The integrated reactor for preparing furfural and levulinic acid by classification from the agricultural and forestry waste biomass according to claim 1, wherein the ratio of the height of the reactor cylinder to the diameter of the reactor cylinder is 3-5: 1.

3. The integrated reactor for preparing furfural and levulinic acid by stages from agricultural and forestry waste biomass according to claim 1, wherein a plurality of steam inlet spray pipes are arranged at the lower part of a reactor cylinder body, and the steam inlet spray pipes are uniformly distributed along the circumference of the cylinder body.

4. The integrated reactor for preparing furfural and levulinic acid by stages from agricultural and forestry waste biomass according to claim 1, wherein a discharge quick-opening valve and a sampling port are arranged at the bottom of a reactor cylinder, and a temperature measuring port and a pressure measuring port are arranged at the top of the reactor cylinder.

5. The integrated reactor for preparing furfural and levulinic acid by classification of the agricultural and forestry waste biomass as claimed in claim 1, wherein the material of the reactor barrel and the stirrer is an acid corrosion resistant material, and the acid corrosion resistant material is hastelloy material, a hastelloy lined composite plate material, enamel lined steel, PFA plastic lined pressure resistant material or polytetrafluoroethylene lined pressure resistant material.

6. The method for preparing furfural and levulinic acid by using agricultural and forestry waste biomass in a grading manner is realized by using the integrated reactor for preparing furfural and levulinic acid by using agricultural and forestry waste biomass in a grading manner, which comprises the following specific steps: uniformly mixing a biomass raw material with a dilute acid solution, feeding the mixture into a reactor barrel through a biomass material raw material inlet, sealing a feed inlet, opening a motor to drive a stirrer to rotate, introducing saturated water vapor through a vapor inlet spray pipe, and performing vapor extraction at 140-160 ℃ through adjusting a vapor outlet adjusting valve to prepare furfural; and after furfural stripping is finished, adding acid liquor from an acid liquor replenishing inlet, introducing saturated water vapor through a vapor inlet spray pipe, introducing vapor into a jacket vapor inlet of a jacket auxiliary heating system for auxiliary heating, and regulating the temperature of the reactor to 160-180 ℃ through a vapor outlet regulating valve for hydrolysis to prepare levulinic acid.

7. The method for preparing furfural and levulinic acid by classification from the agricultural and forestry waste biomass according to claim 6, wherein the dilute acid solution is a dilute sulfuric acid solution, the mass fraction of the dilute sulfuric acid solution is 5-15%, and the amount of sulfuric acid is 0.5-5% of the mass of the biomass raw material; the acid added from the acid liquor replenishing inlet is sulfuric acid, the mass fraction of the sulfuric acid is 5-15%, and the use amount of the sulfuric acid is 0.5-1% of the mass of the biomass raw material.

8. The method for preparing furfural and levulinic acid by classification from the agricultural and forestry waste biomass according to claim 6, wherein the stirring speed of the stirrer is 5-20 revolutions per minute.

9. The method for preparing furfural and levulinic acid by using agriculture and forestry waste biomass in a grading manner according to claim 6, wherein the steam extraction time is 30-120 minutes; the hydrolysis time is 30-180 minutes.

10. The method for preparing furfural and levulinic acid by using agricultural and forestry waste biomass in a grading manner according to claim 6, wherein the pressure of the saturated water vapor is 1.2-1.5 MPa.